Thursday, 22 May 2008

The Power of Pine Needles

Ever wondered why the floor in a pine forest is devoid of life? When any leaves fall they start to decompose and pine needles are no different. However, when pine needles decompose they are Allelopathic - this means they release chemicals which affect (in this case inhibit) the germination of anything around them. In other words, they pollute the surrounding soil in order that no competing species can grow (another reason to hate Leylandii, not that I needed any more).

Allelopathy does have some uses - there are occasions when you will want weed suppression and using an allelopathic mulch can be a good way of achieving this. As we want a native hedgerow around the garden, ultimately underplanted with wild native plants (that's weeds to you!), then the pine needles have to go.

Perfect example of nature in action in these photos. These are taken outside our garden fence. A wonderful mixture of roadside verge including Cow Parsley (Anthriscus sylvestris) which I adore and would love to encourage more of - there is already a small amount in the Secret Garden. There are also some Bluebells.

This is the ground less than 12" away on our side of the fence. Carpet of pine needles = no growth, zilch, zip, nadda, nothing. It will be a long slow job but eventually all of these needles will be swept up and consigned to the bonfire, wonder how long the suppressent chemicals stay in the soil? Absolutely no point putting them on the compost heap - who wants compost that suppresses germination?

Unfortunately it does not seem to have the same effect on Ground Elder .... grrrrrr

Did I mention recently how much I hate Leylandii?


  1. A bit like rhododendrons then - snuff out any competition.

    Your bluebell's looking great - they're all over down south for another year.

  2. My sympathies if you have ground elder, it's in my soft fruit and rose beds, and it's a darn nuisance. Add bindweed, nettles and creeping buttercup to the mix, and you'll know that weeding is a constant bane in my life! Perhaps I need to grow some leylandii - on second thoughts maybe I'll try rhodies!


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